London 2012 - One extraordinary year

In some cases, the system may have led buyers to believe they had been successful in their application, only to find out by email in June 2011 that they had failed.

The first priority group of 20,000 people are those who applied in the ballot and then the second chance sale but missed out in the latter, despite applying for apparently available tickets.

People in this group were contacted by Locog via email on Tuesday 8 May.

The 20,000 people contacted were able to select from any event, including the opening and closing ceremonies, although organisers warned that only a limited number of tickets were available for the two ceremonies.

Olympic Park tickets were not be part of the sale window for this group.

Fans from the two priority groups are limited to one transaction and a maximum of four tickets per person.

These restrictions will be lifted when the remaining tickets go on sale to the public.

New tickets for sale

From Sunday 13 May, one million people who missed out in the first ballot will have five days to buy tickets. Different tickets will be available from 11:00 each day, as follows:

Tickets that are not sold each day will be carried forward for sale the next day. Once fans are successful they will be unable to buy any more tickets in the exclusive five-day period.

Unsold tickets for the Paralympic Games are also set to go on sale from 11:00 BST on 21 May, with further details yet to be announced.

And Locog has said it is releasing new tickets for sale from 29 May, to "help more people get to the Games". These tickets are:

Cycling Road Race at Box Hill, Surrey

Cycling Individual Time Trial at Hampton Court Palace

There will also be tickets available for Wimbledon which will provide access to The Hill and the big screen only

The Orbit - for those who already have access to the Olympic Park on the day they wish to visit the Orbit

Organisers have confirmed there will be a "babes in arms policy" during the Games, which means babies aged 12 months or under will be allowed into all London 2012 venues without a ticket - as long as they are securely strapped to a parent or carer.

But the policy will not apply to events held at Wembley Stadium, St James' Park, Old Trafford and North Greenwich Arena, where licensing rules require everyone to have a ticket.